On Tue, Jul 30, 2019 at 01:02:15PM -0700, Andrew Morton wrote: > On Sat, 27 Jul 2019 14:23:33 +0100 Catalin Marinas <catalin.marinas@xxxxxxx> wrote: > > > Add mempool allocations for struct kmemleak_object and > > kmemleak_scan_area as slightly more resilient than kmem_cache_alloc() > > under memory pressure. Additionally, mask out all the gfp flags passed > > to kmemleak other than GFP_KERNEL|GFP_ATOMIC. > > > > A boot-time tuning parameter (kmemleak.mempool) is added to allow a > > different minimum pool size (defaulting to NR_CPUS * 4). > > btw, the checkpatch warnings are valid: > > WARNING: usage of NR_CPUS is often wrong - consider using cpu_possible(), num_possible_cpus(), for_each_possible_cpu(), etc > #70: FILE: mm/kmemleak.c:197: > +static int min_object_pool = NR_CPUS * 4; > > WARNING: usage of NR_CPUS is often wrong - consider using cpu_possible(), num_possible_cpus(), for_each_possible_cpu(), etc > #71: FILE: mm/kmemleak.c:198: > +static int min_scan_area_pool = NR_CPUS * 1; > > There can be situations where NR_CPUS is much larger than > num_possible_cpus(). Can we initialize these tunables within > kmemleak_init()? We could and, at least on arm64, cpu_possible_mask is already initialised at that point. However, that's a totally made up number. I think we would better go for a Kconfig option (defaulting to, say, 1024) similar to the CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE and we grow it if people report better values in the future. -- Catalin
